Robert chooses to build a HexNum class that can represent integers that are then displayed as hex numbers. There are considerations to be made with handling conversions from existing numeric types and his new HexNum class, conversions to other types, supporting standard comparison methods, and overloading.

All of the above concerns are covered in the post with all the quality and detail you should expect from the RBP blog by now. This post in particular should prove interesting to most Ruby developers who feel happy digging deep (no, this isn't an article for beginners!).